1. Field of the Invention
The present invention relates to a process cartridge and an electrophotographic image forming apparatus.
An electrophotographic image forming apparatus forms images on recording media by using an electrophotographic image forming process. Examples of an electrophotographic image forming apparatus include an electrophotographic copying machine, an electrophotographic printer (such as a laser beam printer and an LED printer), a facsimile apparatus, and a word processor.
A process cartridge is realized by forming at least a charging means, a developing means, and an electrophotographic photosensitive drum into an integral cartridge unit, which is detachably mountable to an image forming apparatus main body. Further, at least a charging means, a developing means, a cleaning means as a process means, and an electrophotographic photosensitive drum are formed into an integral cartridge unit, which is detachably mountable to an image forming apparatus main body.
2. Description of Related Art
In an electrophotographic image forming apparatus using the electrophotographic image forming process, selective exposure corresponding to image information is performed on an electrophotographic photosensitive member uniformly charged by a charging means to thereby form a latent image.
Then, the latent image is developed by a developing means using toner to form a toner image. Thereafter, the toner image formed on the electrophotographic photosensitive member is transferred to a recording medium by a transferring means to thereby effect image formation.
Conventionally, in an image forming apparatus using an electrophotographic image forming process, a process cartridge system is adopted, in which a drum-shaped electrophotographic photosensitive member and a process means acting on the electrophotographic photosensitive member are formed into an integral cartridge, which is detachably mountable to an image forming apparatus main body. In this process cartridge system, the maintenance of the apparatus can be performed by the user without having to rely on a serviceman, whereby a substantial improvement is achieved in terms of operability. Thus, the process cartridge system is widely used in image forming apparatuses.
In a typical construction of such a process cartridge, two frames are joined together. For example, a cleaning frame (first frame) supporting a photosensitive drum, a charger, and a cleaning device and a frame (second frame) formed by connecting together a developing frame supporting a developing means and a toner frame having a toner chamber, are joined together so as to be rotatable around a fulcrum. Then, the two frames are urged around the fulcrum by an elastic member such as a spring to determine the positional relationship between the photosensitive drum and the developing means. The above-described construction is advantageous, for example, in that the pressure force of the developing roller on the photosensitive drum is made appropriate and that a gap is maintained between the photosensitive drum surface and the developing roller surface. Other advantages of this construction include facilitation of the frame formation due to the two-piece frame structure and facilitation of the assembly. In the present invention, the advantages of the above-described conventional technique are further enhanced.
It is an object of the present invention to provide a process cartridge comprising a first frame and a second frame, in which, when a connecting pin for connecting the first frame and the second frame is force-fitted, it is possible to prevent a reduction in the fastening force of the connecting pin due to deformation to enlarge the diameter of the hole into which the connecting pin is force-fitted.
Another object of the present invention is to provide a process cartridge comprising a first frame and a second frame, in which, when a connecting pin for connecting the first frame and the second frame is force-fitted, it is possible to prevent deformation of a charging member support portion supporting a charging member, making it possible to press the charging member against the photosensitive drum in a stable manner.
Still another object of the present invention is to provide a process cartridge in which, when a connecting pin for connecting the first frame and the second frame is force-fitted, it is possible to prevent a reduction in the fastening force of the connecting pin due to deformation to enlarge the diameter of the hole into which the connecting pin is force-fitted, and it is possible to prevent deformation of a charging member support portion supporting a charging member, making it possible to press the charging member against the photosensitive drum in a stable manner.
Also, another object of the present invention is to provide an image forming apparatus and a process cartridge detachably attachable to a main body of an electrophotographic image forming apparatus including: an electrophotographic photosensitive drum; a charging member for charging the electrophotographic photosensitive drum; a developing member for developing with toner an electrostatic latent image formed on the electrophotographic photosensitive drum; a first frame supporting the electrophotographic photosensitive drum and the charging member; a second frame supporting the developing member; a first hole provided in the first frame; a second hole provided in the first frame; a third hole provided in the second frame; a connecting pin passed through the first hole, the second hole, and the third hole to rotatably connect the second frame to the first frame; and a reinforcing portion provided on the downstream side of the first frame with respect to the direction in which the connecting pin is force-fitted so as to restrain deformation of the second hole when force-fitting the connecting pin into the second hole.